AMPEROMETRIC MICROBIOSENSORS FOR DETECTION OF HYDROGEN-PEROXIDE AND GLUCOSE BASED ON PEROXIDASE-MODIFIED CARBON-FIBERS

A mediatorless amperometric microbiosensor can be constructed by immobilizing horseradish peroxidase (HRP) onto the surface of carbon fibers. Several types of carbon fibers were tested. The best microelectrode, constructed by immobilizing HRP on high modulus type (GH) carbon fibers, presented a linear response range between 20 mu M and 2.5 mM H2O2 and a detection limit of 0.2 mu M H2O2, calculated as twice the signal-to-noise ratio. When HRP was coimmobilized with hydrogen peroxide-producing glucose oxidase (GOD), a glucose sensor could be constructed with a linear potential range between 20 and 160 mu M glucose, with a detection limit of 20 mu M. The detection of the substrates was performed at a working potential of 0 mV (vs. SCE) at pH 6.0.